RESUMO
In this letter, we describe a novel gain measurement approach for semiconductor edge-emitting lasers, with which TE and TM gain spectra can be easily obtained by collecting the amplified spontaneous emissions at dual facets of the device. An unstrained and continuously-operated GaAs/AlGaAs single quantum well laser strip is used to illustrate this method. The measured gain spectra are compared with theoretical gain curves to analyze the gain polarization characteristics and the relevant subband structure in the valence band of the well using the measured gain spectra.
Assuntos
Análise de Falha de Equipamento/instrumentação , Análise de Falha de Equipamento/métodos , Lasers Semicondutores , Amplificadores Eletrônicos , Desenho de EquipamentoRESUMO
In this paper, a shear force scanning near-field fluorescence microscope combined with a confocal laser microspectrofluorometer is described. The shear force detection is realized based on a bimorph cantilever, which provides a very sensitive, reliable, and easy to use method to control the probe-sample distance during scanning. With the system, high-quality shear force imaging of various samples has been carried out. Furthermore, simultaneous shear force and near-field fluorescence imaging of biological cells has also been realized. As an example, we especially present the result on the distribution of P-glycoprotein in the plasma membrane of human small cell lung cancer cells, suggesting that the system would be a promising tool for biological applications.
Assuntos
Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Carcinoma de Células Pequenas/ultraestrutura , Neoplasias Pulmonares/ultraestrutura , Microscopia Eletrônica de Varredura/instrumentação , Microscopia Eletrônica de Varredura/métodos , Carcinoma de Células Pequenas/metabolismo , Linhagem Celular Tumoral , Humanos , Neoplasias Pulmonares/metabolismo , Microscopia Confocal/instrumentação , Microscopia Confocal/métodosRESUMO
A non-optical bimorph-based tapping-mode force sensing method for tip-sample distance control in scanning near-field optical microscopy is developed. Tapping-mode force sensing is accomplished by use of a suitable piezoelectric bimorph cantilever, attaching an optical fibre tip to the extremity of the cantilever free end and fixing the guiding portion of the fibre to a stationary part near the tip to decouple it from the cantilever. This method is mainly characterized by the use of a bimorph, which carries out simultaneous excitation and detection of mechanical vibration at its resonance frequency owing to piezoelectric and anti-piezoelectric effects, resulting in simplicity, compactness, ease of implementation and lack of parasitic optical background. In conjugation with a commercially available SPM controller, tapping-mode images of various samples, such as gratings, human breast adenocarcinoma cells, red blood cells and a close-packed layer of 220-nm polystyrene spheres, have been obtained. Furthermore, topographic and near-field optical images of a layer of polystyrene spheres have also been taken simultaneously. The results suggest that the tapping-mode set-up described here is reliable and sensitive, and shows promise for biological applications.